Method of and apparatus for communicating

ABSTRACT

A system for effecting communication between first and second radio transceivers, comprises a communicator for effecting communication between the first and second radio transceivers over a first channel; a determiner for determining the distance between the transceivers, and for determining if the distance falls below a predetermined threshold; and a channel charger responsive to a positive determination, for effecting direct mode communication between the transceivers over a second channel.

FIELD OF THE INVENTION

This invention relates to a method of communicating between first andsecond radio transceivers. This invention relates also to a system, andto a radio transceiver.

BACKGROUND OF THE INVENTION

Various radio channel types exist today for use by portable radiotransceivers, global system mobiles (GSM) speech channels, generalpacket radio service (GPRS), Bluetooth and wireless local area network(WLAN) being examples of such channel types. Furthermore, the universalmobile telephone system (UMTS) allows the transfer of audio-visualinformation in both directions between portable radio transceivers. Theterm now adapted for portable radio transceivers of the UMTS standard ismobile station (MS), and this term is used hereafter to describe amobile radio transceiver capable of communicating in any system.

With many MSs being equipped to communicate with two or more differentchannel types, it has become common for a user of an MS to have todecide which type of communication channel to use, which can constitutean inconvenience.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a methodof communicating, the method comprising: effecting communication betweenfirst and second radio transceivers via a telecommunications networkover a first channel; determining the distance between the first andsecond radio transceivers; determining whether the distance between thetwo transceivers meets a predetermined threshold; and in response to adetermination that the threshold is met, effecting direct modecommunication between the first and second radio transceivers over asecond channel.

The invention also includes a radio transceiver, comprising: acommunicator for communicating with a remote radio transceiver via atelecommunications network over a first channel; a determiner fordetermining the distance between the transceiver and the remotetransceiver, and for determining whether the distance meets apredetermined threshold; and a channel charger, responsible to adetermination that the threshold is met, for effecting direct modecommunication between the transceiver and the remote transceiver over asecond channel.

The second channel may have a greater bandwidth than the first channeland the first and second channels may be of different channel types. Themethod may include, prior to the effecting direct mode communicationstep, estimating the quality of the second channel. The determiningsteps may be carried out at the first radio transceiver and the distancedetermination step may include determining the locations of the firstand second radio transceivers.

The location determination may involve a satellite-based position systemor may involve triangulating from plural fixed radio transceivers,preferably forming part of the telecommunications network.

The direct mode communication step may be effected only if a bandwidthor other service demand exceeds the capability of the first channel.

Moreover, the threshold can be dependent on, preferably equal to, thesum of the radio coverage of the first and second radio transceivers.

The invention also extends to a system for effecting communicationbetween first and second radio transceivers, comprising: a communicatorfor effecting communication between the first and second radiotransceivers over a first channel; a determiner for determining thedistance between the transceivers, and for determining if the distancemeets a predetermined threshold; and a channel charger responsive to adetermination that the threshold is met, for effecting direct modecommunication between the transceivers over a second channel.

The invention will now be described, by way of example only, withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a mobile station according to oneaspect of the invention;

FIG. 2 is a schematic diagram of a telecommunication system according toone aspect of the invention and including the mobile station of FIG. 1;

FIG. 3 is a flow chart illustrating operation of the mobile station ofFIG. 1; and

FIG. 4 is a chart showing signalling effected according to oneembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to FIG. 1, a first mobile station (MS) 10 comprises generallya housing 11, an antenna 12, which is connected to transmit and receivecircuitry 13, and a central processing unit (CPU) 14. The CPU 14 isconnected to the transmit and receive circuitry 13 in four parallelpaths 15-18, each path including a respective one of a Bluetooth module19, a UMTS speech channel module 20, a WLAN module 21 and a UMTSaudio-visual module 22. A database 24 containing threshold information,also is connected to the CPU 14. Each of the modules 19 to 22 isconfigured to allow the first MS 10 to communicate via radio over adifferent respective channel type. Moreover, each of the channel typeshas a different bit rate, which equates to bandwidth, namely around 1000kb/s for UMTS speech, 1 Mb/s for Bluetooth, 10 Mb/s for UMTS A-V, andaround 100 MB/s for WLAN. The first MS 10 optionally includes a globalpositioning system (GPS) receiver 23 which is arranged, in response to arequest by the CPU 14, to determine the location of the MS, and toprovide location information to the CPU. A receiver operable withanother positioning system (such as Glonass or the proposed Galileo)could be used in place of the GPS receiver 23.

Operation of the MS 10 in a telecommunications system will now bedescribed with reference to FIG. 2.

In FIG. 2, the MS 10 is shown communicating with a first base station(BS) 30 of a UMTS system 31. Second to fourth BSs on 32-34 are shown,along with their respective areas of coverage (the boundaries of whichare given by dotted-line circles). Second to fourth MSs 35-38, are shownin communication with, various ones of the BSs 30, 32-34.

In this example, the first MS 10 is connected for speech communicationwith the second MS 35 over a UMTS speech channel. To this end, the firstMS 10 is connected to the BS 30 via a two-way UMTS speech channel, as isthe second MS, 35. Alternatively, the second MS 35 could be connectedvia the second BS 32, in which case data would pass between the secondBS and the first BS 30 via the network 31, since the second MS is withinthe area of coverage of both the first and second BSs. It is notimportant for the purpose of this embodiment which BS or BSs the firstand second MSs 10, 35 are using for communication.

On determination that the bandwidth of the channel being used forcommunication between the first and second MSs 10, 35, which in thisexample is a UMTS speech channel, is not sufficiently high tocommunicate, the first MS sets a ‘more bandwidth desired’ flag (notshown) to TRUE. Examples of situations in which this might occur arewhen video signals are being communicated, and it is determined that ahigher quality of picture is required, or when it is desired to sendother data, e.g. gaming data, along with normal speech call data.Another situation when this might occur is when the channel type (andhence the bandwidth) is selected by a user or the users on the basis ofcost effectiveness, when a higher bandwidth channel would be desired;for example when a speech call is in progress when a videophone callwould be preferred. Since direct mode communication does not involve thetransmission of large amounts of data over a network, it may be muchcheaper than network calls, or even without charge. As long as the ‘morebandwidth desired’ flag remains TRUE, the software operation given bythe flowchart of FIG. 3 is run on the first MS 10.

Referring to FIG. 3, the operation begins in this instance at step 40,which describes the connection status at this time. In this context, itwill be appreciated that ‘global connection’ refers to connection viathe base stations 30, 32-34 of the network 31. At step 41, the first MS10 determines its location using its GPS receiver 23, and receivesinformation identifying the location of the second MS 35.

At step 42, the positions of the two MSs 10, 35 are compared, and thedistance between them calculated. This distance is then compared tovalues stored in a table which relate to predetermined feasibilityparameters. The operation of step 42 is performed relativelyinfrequently, so as to save resources, e.g. processing resources and toavoid the need for frequent sending of location and other subsidiaryinformation over the network 31. A decision is made at step 43 as towhether the connection is potentially feasible, and return is made tostep 41 if a negative, decision is made. Otherwise, the positions of theMSs 10, 35 are compared again at step 44, and the distance between themcompared to the maximum permissible distance in step 45. A threshold,which is the maximum permissible distance, is set at a value equal tothe sum of the radio coverage of the first and second MSs, whichcoverages are made available to the first MS 10 in any suitable manner.The threshold and the maximum permissible distances are stored in thedatabase 24. This calculation is made significantly more frequently thanthe calculation of step 42. If the threshold is exceeded, a NO resultreturns the operation to step 41. If the threshold is not exceeded, aYES result causes the operation to progress to step 46. Here, directmode communication is established between the first and second MSs 10,35 in any suitable manner. The global communication may remain in placeor it may be disconnected. By step 47, local connection, or direct modecommunication, is established and on.

At step 48, the first MS 10 again determines its location using the GPSreceiver, receives location information about the second MS 35, anddetermines the distance therebetween. At step 49, this distance iscompared with the threshold used in step 45, and a decision made as towhether the threshold is exceeded at step 50 with a NO result returningthe operation to step 48, and a YES result causing progression to step51. It will be appreciated that a YES result is obtained from step 50only when the first and second MSs 10, 35 have moved apart so that theirradio coverages no longer overlap. In this case, the operation takes theappropriate step, step 51, of switching communication from local (directmode) to global (i.e. via at least one BS 30). If the global connectionwas broken at step 41, then step 50 involves establishing a globalconnection, in any convenient manner.

In a further embodiment (not shown), the switching of a globalconnection to a local connection is carried out only if an MS determinesthat a channel of sufficiently high quality can be established. This isachieved by the sending of data from the first MS via the first BS 30,indicating the channel which is to be used, which information is thenpassed onto the second MS 35. The first MS 10 then transmits some testdata via the identified channel, and this data is received by the secondMS 35. The bit error rate (BER) of the received data is calculated in aconventional manner, and the BER transmitted to the first MS 10 eitherdirectly or using the global connection. The connection is switched fromglobal to local at step 46 only if the first MS determines from the BERreceived from the second MS 35 that the propagation channel between thefirst and second MSs 10, 35 is of sufficiently high quality. Channelquality is determined continuously, along with the distance between thefirst and second MSs 10, 35, for the purpose of determining whether aswitch from local to global communication should be made.

Many variations of this are possible. For example, any other measure ofchannel quality may be made and used for the purpose of deciding whetherto switch, examples being received signal strength and packet errorrate. Also, a measure of the quality of the propagation channel from thesecond MS 35 to the first MS 10 may be made and this may be dependent onhow much data is required to be transmitted across that channel.

The operation of the flowchart of FIG. 3 does not need to be carried outby the first MS 10. Although it is preferred that the operation iscarried out by the MS which determines that a higher bandwidth channelof communication is desired, this operation may be carried out insteadby another MS or by the BS 30 or some other part of the network 31.Running the operation of the FIG. 3 flowchart other than in the first MSallows it to be of simpler design.

Reference is now made to FIG. 4, which is a signalling chart having thefirst MS 10 on the left hand side (Terminal A), the second MS 35 on theright hand side (Terminal B), and the network 31 in the centre.

Referring to FIG. 4, connection established signals 60, 61 are passedfrom Terminal A to network 31 and from there, to terminal B respectivelyonce a channel has been allocated respectively. Connected signals 62, 63are sent from terminal B and from the network 31, respectively, inresponse. Communication between the terminals A and B is thenestablished over a first channel, as is indicated at 64. The network 31subsequently, and while the channel 64 is still open, transfers locationinformation to terminal B and to terminal A with signals 65 and 66. Inthe embodiment of FIG. 3, it is not necessary to send signals 65 and 66because location information is not stored on the network 31. In otherembodiments (not shown) however, a location information network (whichmay or may not form part of the network 31) is used to calculate and tohold information about the locations of the MSs 10 and 35, and thisinformation is passed to one or both of the MSs before direct-modecommunication can be established. Identification and locationinformation, as well as any other required information, is then passedbetween the terminals by signals 67 to 70. Afterwards, direct modecommunication is established by the sending of a connectionestablishment signal 71 directly from terminal A to terminal B and by acommunication signal 72 sent in reply. Direct mode communication is thenestablished at 73.

The location of the first and/or second MSs 10, 35 may be determined inany suitable manner, such as by triangulating signals from plural basestations of known locations as is known. The triangulation calculationsmay be carried out by the network 31 or by the relevant MS 10, 35.

Location information for each MS may be stored by the network 31, and beaccessible by any station as and when required. Location information maybe transmitted to an MS by SMS message, which is particularly convenientsince SMS messages can be received without interruption of any ongoingspeech call.

In an alternative embodiment (not shown), the second channel has abandwidth equal to or less than the first channel.

1. A method of communicating, the method comprising: effectingcommunication between first and second radio transceivers via atelecommunications network over a first channel; determining thedistance between the first and second radio transceivers; determiningwhether the distance between the two transceivers meets a predeterminedthreshold; and in response to a determination that the threshold is met,effecting direct mode communication between the first and second radiotransceivers over a second channel.
 2. A method as claimed in claim 1,in which the second channel has a greater bandwidth than the firstchannel.
 3. A method as claimed in claim 1, further comprising, prior tothe effecting direct mode communication step, estimating the quality ofthe second channel.
 4. A method according to claim 1, in which thedetermining steps are carried out at the first radio transceiver.
 5. Amethod according to claim 1, in which the distance determination stepincludes determining the locations of the first and second radiotransceivers.
 6. A method as claimed in claim 5, in which the locationdetermination involves a satellite-based position system.
 7. A method asclaimed in claim 1, in which the location determination involvestriangulating from plural fixed radio transceivers, preferably formingpart of the telecommunications network.
 8. A method as claimed in claim1, in which the first and second channels are of different channeltypes.
 9. A method as claimed in claim 1, in which the direct modecommunication step is effected only if a bandwidth or other servicedemand exceeds the capability of the first channel.
 10. A method asclaimed in claim 1, in which the threshold is dependent on the sum ofthe radio coverage of the first and second radio transceivers.
 11. Aradio transceiver, comprising: a communicator for communicating with aremote radio transceiver via a telecommunications network over a firstchannel; a determiner for determining the distance between thetransceiver and the remote transceiver, and for determining whether thedistance meets a predetermined threshold; and a channel charger,responsible to a determination that the threshold is met, for effectingdirect mode communication between the transceiver and the remotetransceiver over a second channel.
 12. A radio transceiver as claimed inclaim 11, in which the second channel has a greater bandwidth than thefirst channel.
 13. A radio transceiver as claimed in claim 11, furthercomprising an estimator arranged to estimate the quality of the secondchannel.
 14. A radio transceiver as claimed in claim 11, including asatellite positioning receiver, arranged to calculate the location ofthe transceiver.
 15. A radio transceiver as claimed in claim 11, inwhich the first and second channels are of different types.
 16. A systemfor effecting communication between first and second radio transceivers,comprising: a communicator for effecting communication between the firstand second radio transceivers over a first channel; a determiner fordetermining the distance between the transceivers, and for determiningif the distance meets a predetermined threshold; and a channel chargerresponsive to a determination that the threshold is met, for effectingdirect mode communication between the transceivers over a secondchannel.